1. Technical Field
The present invention relates to end mills in general, and to end mill cutting edge geometries in particular.
2. Background Information
A conventional end mill operable to remove material from a workpiece typically includes a shank section and a fluted section. The fluted section includes a plurality of helical teeth, each having a cutting surface and a relief wall that intersect with one another to form a cutting edge. The cutting edges of the rotating end mill engage the workpiece and cause “chips” of the workpiece to separate.
The geometry of the helical teeth, and in particular the cutting edge, greatly influences the performance and life of the tool, and the workpiece finish produced by the tool. The cutting edge of a helical tooth has historically been created by grinding the cutting surface and the relief wall of the tooth, leaving a surface finish typically in the range of between eight and sixteen microns (8-16 μm). Although a surface finish in the range of 8-16 μm is relatively smooth to the naked eye, it contains a plurality of peaks and valleys that will give the cutting edge a serrated-type finish. It is our experience that such a serrated cutting edge can undesirably influence the performance of an end mill by making it more susceptible to undesirable chatter, and negatively affect the life of the tool by making the cutting edge more prone to mechanical failure; e.g., chipping. In addition, a serrated cutting edge can also undesirably limit the smoothness of the workpiece surface finish produced by the tool.
It is known to modify a cutting edge by placing a wire brush in contact with the cutting edge. Modifying a cutting edge in this manner does not, however, produce a uniform cutting edge and therefore does not resolve the aforesaid performance, durability, and finish issues associated with the cutting edge.
What is needed, therefore, is an end mill having helical teeth that provides improved performance, durability and finish characteristics relative to existing end mills.